1. Field of Invention
A novel mixed metal oxide catalyst for the production of acrylic acid through catalytic vapor phase partial oxidation of propane and its use for one stage selective production of acrylic acid and acrolein at lower temperatures.
2. Description of Related Art
Several publications are referenced in this application. These references describe the state of the art to which this invention pertains and are hereby incorporated by reference.
The two stage vapor phase oxidation of propylene for the production of acrylic acid is known to the art. However, there is no commercial process that exists based on propane oxidation to acrylic acid. The production of acrylic acid from propane would be more attractive because of the significant price difference between propane and propylene.
There are few references reported in the literature relating to the production of acrylic acid from propane. U.S. Pat. No. 5,198,580 discloses a process for partial oxidation of propane to yield acrylic acid, propylene, acrolein, acetic acid and carbon oxides by the reaction of propane in admixture with a molecular oxygen-containing gas in a reaction zone with a catalyst containing Bi.sub.b Mo.sub.c V.sub.v A.sub.a D.sub.d E.sub.e O.sub.x ; where A is one or more of K, Na, Li, Cs and Tl; D is one or more of Fe, Ni, Co, Zn, Ce and La; E is one or more of W, Nb, Sb, Sn, P, Cu, Pb, B, Mg, Ca and Sr; values for a, d and e are from 0 to 10, b is from 0.1 to 10, c is from 0.1 to 20, v is from 0.1 to 10, c:b is from 2:1 to 30:1 and v:b is from 1:5 to 1 to 8. The acrylic acid yield achieved using the bismuth molybdate type of catalyst is 5.4% at 19% conversion of propane at a pressure of 20 psig and a temperature of 400.degree. C.
European patent EP 0 608 838 A2 to Takashi et al. discloses a method of producing an unsaturated carboxylic acid, mostly in the explosive regime of the propane, air and water mixture at 380.degree. C. in the presence of a catalyst containing a mixed metal oxide of MoVTeXO, wherein X is at least one element selected from bismuth, cerium, indium, tantalum, tungsten, titanium, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum and antimony, wherein the proportion of the respective essential components are based on the total amount of the essential components exclusive of oxygen and satisfy the following formulae: 0.25&lt;V.sub.Mo &lt;0.98, 0.003&lt;V.sub.v &lt;0.5, 0.003&lt;V.sub.x &lt;0.5, wherein V.sub.Mo, V.sub.v, V.sub.Te and V.sub.x are molar fractions of Mo, V, Te and X.
Recently, Takashi et al. disclosed in another JP Patent No. 10 45 643 [98 45 643--Feb. 1998] the formation of acrylic acid and acrolein in the presence of P.sub.a Mo.sub.b V.sub.c W.sub.d X.sub.e O.sub.n (X=Nb, Ta, Ti, Zr, Sb; if a=1 then b=1-18, c=0-4, d=0-4 and e=0.05-20) at 380.degree. C. achieving a yield 0.9% to acrolein and 3.5% to acrylic acid at 12% propane conversion.
The above-referenced catalysts disclosed in the literature result in low yields of acrylic acid at relatively high temperatures and produce propylene as one of the significant by-products. Propylene can be expensive to separate, especially in a recycling mode of operation.
Thus, none of the prior art discloses or suggests catalysts which provide for the selective production of acrylic acid and acrolein at low temperatures through a gas phase partial oxidation process of propane.
It would be desirable to provide a catalyst designed in such a way that a single catalyst selectively produces acrylic acid and acrolein from propane without the significant production of intermediates such as propylene.